Control of interaction between an apparatus and a user based on user&#39;s state of reaction

ABSTRACT

An apparatus estimates, based on an input from a user to an interaction performed during a conversation between the user and the apparatus, an interest degree indicating a degree of interest of the user in a first topic included in the interaction, and estimates, based on the input from the user to the interaction, acceptability of the interaction by the user. The apparatus selects, in accordance with the interest degree and the acceptability, as an operation mode for performing the interaction, one of a first mode of leaving an interaction initiative to the user and a second mode in which the interaction proceeds under an initiative of a system for a specific topic. The apparatus generates interaction data according to the selected operation mode, and causes an output device to output the generated interaction data.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of theprior Japanese Patent Application No. 2018-228410, filed on Dec. 5,2018, the entire contents of which are incorporated herein by reference.

FIELD

The embodiments discussed herein are related to control of interactionbetween an apparatus and an user based on user's state of reaction.

BACKGROUND

Voice guidance generating devices that provide voice guidance forexecuting commands of applications such as transmission of electronicmail have been disclosed. Such a voice guidance generating devicedetermines an interaction form with the user according to the type ofguidance specified in advance, such as a user initiative type or asystem initiative type.

An interaction device is disclosed in which, based on the magnitude of amotion of each part of the body of the user when the voice input of theuser changes from presence to absence, it is determined whether the useris going to continue to utter a word or the user is going to transferthe right of utterance to a system.

Related techniques are disclosed in, for example, Japanese Laid-openPatent Publication No. 2002-342065 and Japanese Laid-open PatentPublication No. 2002-108388.

SUMMARY

According to an aspect of the embodiments, an apparatus estimates, basedon an input from a user to an interaction performed during aconversation between the user and the apparatus, an interest degreeindicating a degree of interest of the user in a first topic included inthe interaction, and estimates, based on the input from the user to theinteraction, acceptability of the interaction by the user. The apparatusselects, in accordance with the interest degree and the acceptability,as an operation mode for performing the interaction, one of a first modeof leaving an interaction initiative to the user and a second mode inwhich the interaction proceeds under an initiative of a system for aspecific topic. The apparatus generates interaction data according tothe selected operation mode, and causes an output device to output thegenerated interaction data.

The object and advantages of the invention will be realized and attainedby means of the elements and combinations particularly pointed out inthe claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating a schematic configuration of aninteraction control system according to each embodiment;

FIG. 2 is a functional block diagram of an interaction device accordingto each embodiment;

FIG. 3 is a functional block diagram of an interaction control deviceaccording to each embodiment;

FIG. 4 is a graph illustrating an example of time-sequential changes inprobability and acceptability;

FIG. 5 is a graph illustrating an example of time-sequential changes inprobability and acceptability;

FIG. 6 is a graph illustrating an example of time-sequential changes inprobability and acceptability;

FIG. 7 is a block diagram illustrating a schematic configuration of acomputer that functions as an interaction device according to eachembodiment;

FIG. 8 is a block diagram illustrating a schematic configuration of acomputer that functions as an interaction control device according toeach embodiment;

FIG. 9 is a flowchart illustrating an example of a converting processaccording to each embodiment;

FIG. 10 is a flowchart illustrating an example of an interaction controlprocess according to a first embodiment;

FIG. 11 is a flowchart illustrating an example of an interaction controlprocess according to each embodiment; and

FIG. 12 is a flowchart illustrating an example of an interaction controlprocess according to a second embodiment.

DESCRIPTION OF EMBODIMENTS

The voice guidance generating device described above provides guidancefor performing processes determined in advance, such as executingcommands of applications, and there have been some cases where acontinuous interaction may not be performed without boring the user. Theinteraction device described above is intended to determine which of theuser and the system has the right of utterance, and there have been somecases where a continuous interaction may not be performed without boringthe user.

It is desirable that interactions between people and computers continuewithout boring the user.

Hereinafter, examples of embodiments of the disclosed techniques will bedescribed in detail with reference to the accompanying drawings.Examples of forms in which the disclosed techniques are applied to aninteraction control system for a conversation between a user and acomputer will be described.

First Embodiment

With reference to FIG. 1, the configuration of an interaction controlsystem 10 according to the present embodiment will be described. Asillustrated in FIG. 1, the interaction control system 10 includes aninteraction device 12 and an interaction control device 14. Theinteraction device 12 and the interaction control device 14 are eachcoupled to a network N.

The interaction device 12 is installed in the home of a user, a facilityvisited by the user, or the like and interacts with the user by voiceunder control of the interaction control device 14. Examples of theinteraction device 12 include an artificial Intelligence (AI) speakerand a communication robot.

The interaction control device 14 is installed in a data center or thelike and controls an interaction with a user by using the interactiondevice 12. Examples of the interaction control device 14 include aserver computer and a cloud server.

The interaction control system 10, in which an interaction with a useris performed, is able to collect more amounts of information from theuser by causing interactions with the user to continue. The interactioncontrol system 10 is able to provide information more appropriate forthe user by collecting more amounts of information from the user. Thisleads to more frequent usage of the interaction control system 10 by theuser, which enables the interaction control system 10 to collect stillmore amounts of information from the user. As a result, information moreappropriate for the user may be provided.

Accordingly, to cause interactions with the user to continue, theinteraction control system 10 according to the present embodiment hastwo operation modes, which are a listening mode of leaving theinitiative of an interaction to the user and a specific topic mode inwhich an interaction on a specific topic proceeds under the initiativeof the system. The interaction control system 10 selects which of thelistening mode and the specific topic mode, as an operation mode forperforming an interaction, in accordance with the probability of theinterest (hereinafter referred simply as the probability) that the useris interested in a topic included in an interaction and theacceptability of the interaction by the user (hereinafter referredsimply as the acceptability). The listening mode corresponds to a firstmode of the disclosed techniques and the specific topic mode correspondsto a second mode of the disclosed techniques. The probability that auser is interested in a topic, as used herein, corresponds to the degreeof interest of the user in the topic.

With reference to FIG. 2, the functional configuration of theinteraction device 12 according to the present embodiment will bedescribed. As illustrated in FIG. 2, the interaction device 12 includesa conversion unit 20, a transmitting unit 22, and a receiving unit 24.

The conversion unit 20 receives utterances of a user via a voice inputdevice 66 described later and converts voice data representing thereceived utterances to text data. The utterances of the user input viathe voice input device 66 are an example of input from the user to aninteraction in the disclosed techniques. The conversion unit 20 convertstext data representing utterances received by the receiving unit 24described later to voice data. The conversion unit 20 makes responseutterances by causing synthesized voice data, which represents theresponse utterances, to be output from a voice output device 67described later. The response utterances output from the voice outputdevice 67 by the interaction device 12 are an example of an interactionoutput of the disclosed techniques. Examples of the interaction outputinclude synthesized voice output.

The transmitting unit 22 transmits text data representing utterances ofthe user obtained through conversion by the conversion unit 20 to theinteraction control device 14. The receiving unit 24 receives text datarepresenting utterances transmitted from the interaction control device14.

With reference to FIG. 3, the functional configuration of theinteraction control device 14 according to the present embodiment willbe described. As illustrated in FIG. 3, the interaction control device14 includes an analysis unit 30, a probability estimation unit 32, anacceptability estimation unit 34, a selection unit 36, a generating unit38, and an output unit 40.

The analysis unit 30 receives text data representing utterances of theuser transmitted from the interaction device 12. The analysis unit 30performs known natural language processing on the received text data,thereby performing morphological analysis, determining the meaning of asentence, such as a question sentence or a sentence in an affirmativeform, a negative form, or another form, and performing analysis such asestimation of emotion of the user.

The probability estimation unit 32 estimates, from the utterances of theuser, a topic in which the user is interested, and estimates theprobability that the user is interested in the estimated topic. Examplesof the topic include politics, the economy, education, sports, andentertainment. The classifications of topics are not limited to thisexample and, for example, sports may be finely classified into baseball,soccer, and so on. The probability according to the present embodimentrepresents the likelihood that the user is interested in a topic, andthe greater the likelihood, the greater value the probability has.

For example, the probability estimation unit 32 estimates a topic inwhich the user is interested, for example, from the frequency ofoccurrences of a term regarding the topic in utterances of the user. Theprobability estimation unit 32 normalizes the probability to a valuegreater than or equal to 0 and less than or equal to 1, and estimatesthe probability by increasing and decreasing the probability asindicated below in (A) to (D). In the present embodiment, for example,topic options such as politics, the economy, education, sports, andentertainment are predetermined and, for each option, the probabilityestimation unit 32 increases and decreases the probability fromutterances of the user as indicated below in (A) to (D).

(A) When the user utters a term related to a topic, the probabilityestimation unit 32 increases the probability of the topic.

(B) When the response of the user to utterances regarding a topic of theinteraction device 12 is affirmative, the probability estimation unit 32increases the probability of the topic.

(C) When the response of the user to a question about a topic uttered bythe interaction device 12 is a response within the assumed range, theprobability estimation unit 32 increases the probability of the topic.

(D) With lapse of time, the probability estimation unit 32 decreases theprobability of the topic.

The form is illustrated in which the value (for example, 0.1) by whichthe probability is increased or decreased in (A) to (D) is predeterminedthrough an experiment or the like.

The acceptability estimation unit 34 estimates the acceptability of aninteraction by the user from the meaning of a sentence, such as anaffirmative or negative meaning, in the utterances of the user, aresponse to the utterances made by the interaction device 12, theutterance time, the emotion of the user, and so on. The acceptabilityaccording to the present embodiment represents the degree to which theuser accepts an interaction with the interaction control system 10, andthe higher the degree, the greater the value. The acceptability alsorepresents the degree to which the user is satisfied with an interactionwith the interaction control system 10.

The acceptability estimation unit 34 normalizes the acceptability to avalue greater than or equal to 0 and less than or equal to 1, andestimates the acceptability by increasing and decreasing theacceptability as indicated below in (E) to (K).

(E) The acceptability estimation unit 34 decreases the acceptabilitywhen the meaning of a sentence of utterances from the user is negative.

(F) The acceptability estimation unit 34 decreases the acceptabilitywhen, despite the lapse of a predetermined time period or more sinceutterances were made by the interaction device 12, there is no responsefrom the user.

(G) The acceptability estimation unit 34 increases the acceptabilitywhen the number of times the user utters a word in the immediatelyprevious predetermined period is larger than a predetermined number.

(H) The acceptability estimation unit 34 increases the acceptabilitywhen the number of backchannel responses to utterances from theinteraction device 12 is larger than a predetermined number.

(I) The acceptability estimation unit 34 increases the acceptabilitywhen the user responds to a topic in utterances of the interactiondevice 12 with the same or similar topic.

(J) The acceptability estimation unit 34 increases the acceptabilitywhen the utterance time spent in one uttering of the user is longer thanor equal to a predetermined time.

(K) The acceptability estimation unit 34 increases the acceptabilitywhen the emotion of a user estimated from utterances of the user is anaffirmative emotion, and decreases the acceptability when the estimatedemotion is a negative emotion.

The form is illustrated in which the value (for example, 0.1) by whichthe acceptability is increased or decreased in (E) to (K) ispredetermined through an experiment or the like. The text data,probability, and acceptability representing utterances of the user arestored as histories in a given storage area of the interaction controldevice 14.

The acceptability estimation unit 34 may use an intonation of the voiceof the user for estimation of the acceptability. In the case where theinteraction control system 10 includes an imaging device to capture anexpression of the user, the acceptability estimation unit 34 may use theexpression of the user included in an image captured by the imagingdevice for estimation of the acceptability.

The selection unit 36 selects which of the listening mode and thespecific topic mode, as an operation mode for performing an interaction,in accordance with the probability estimated by the probabilityestimation unit 32 and the acceptability estimated by the acceptabilityestimation unit 34.

For example, the selection unit 36 selects the listening mode as theoperation mode when the current operation mode is the listening mode andwhen there is no topic the probability of which is greater than or equalto a certain value. Accordingly, in this case, the listening modecontinues.

The selection unit 36 selects the listening mode as the operation modewhen the current operation mode is the listening mode, when there is atopic the probability of which is greater than or equal to the certainvalue, and when the acceptability is greater than or equal to athreshold TH1 and the reduction in acceptability is less than athreshold TH2. Accordingly, in this case, the listening mode continues.The threshold TH1 is an example of a first threshold in the case wherethe current operation mode in the disclosed techniques is a first mode,and the threshold TH2 is an example of a second threshold in the casewhere the current operation mode in the disclosed techniques is thefirst mode.

When the current operation mode is the listening mode, when there is atopic the probability of which is greater than or equal to the certainvalue, and when the acceptability is less than or equal to the thresholdTH1 or the reduction in acceptability is greater than or equal to thethreshold TH2, the selection unit 36 selects the specific topic mode asthe operation mode. In this case, the selection unit 36 selects a topicthe probability of which is greater than or equal to the certain value,as a topic for which the interaction proceeds in the specific topicmode. Accordingly, in this case, the operation mode is switched from thelistening mode to the specific topic mode in which an interactionproceeds for a topic the probability of which is greater than or equalto the certain value. In the case where there are a plurality of topicsthe probability of each of which is greater than or equal to the certainvalue, the selection unit 36 may randomly select one topic among theplurality of topics the probability of each of which is greater than orequal to the certain value or, in order to perform an interaction for anew topic, the selection unit 36 may select a topic for which aninteraction has not occurred within the immediately previouspredetermined period. In such a case, the selection unit 36 may select atopic the probability of which is highest among the plurality of topicsthe probability of each of which is greater than or equal to the certainvalue. In this case, a topic to be selected may be the same as or may bedifferent from the topic that is dealt with by the probability used forcalculations of the thresholds TH1 and TH2 described later.

The reduction in acceptability according to the present embodimentrepresents the amount of reduction in acceptability per unit time, andthe higher the degree to which the acceptability is reduced, the largerthe reduction in acceptability.

With regard to the threshold TH1 according to the present embodiment,the higher the probability, the larger the threshold TH1. Thereby, inthe case where the current operation mode is the listening mode, thehigher the probability of a topic, the more easily the operation mode isswitched to the specific topic mode even when the acceptability is high.For example, the threshold TH1 is calculated, for example, by thefollowing equation (1). In equation (1), c represents the probability,TH1max represents the maximum value (for example, 0.8) of the thresholdTH1, and TH1 min represents the minimum value (for example, 0.2) of thethreshold TH1.

TH1=c×TH1max+(1−c)×TH1min  (1)

The threshold TH1 may be calculated, for example, by the followingequation (2). In equation (2), α and β represent constants (for example,α=0.3 and β=0.7) that satisfy 0<α<β<1. The threshold TH1 calculated byequation (2) is TH1 min when c (probability)<α and is TH1max when c>β.When α≤c≤β, the threshold TH1 satisfies TH1min≤TH1≤TH1max, where thelarger the probability c, the larger the threshold TH1.

$\begin{matrix}\left. \begin{matrix}{{{{TH}\; 1} = {{TH}\; 1\mspace{14mu} \min \mspace{14mu} \left( {{{when}\mspace{14mu} c} < \alpha} \right)}}\mspace{365mu}} \\{{{TH}\; 1} = {{\frac{c - \alpha}{\beta - \alpha} \times {TH}\; 1\mspace{14mu} \max} + {\frac{\beta - c}{\beta - \alpha} \times {TH}\; 1\mspace{14mu} \min \mspace{14mu} \left( {{{when}\mspace{14mu} \alpha} \leq c \leq \beta} \right)}}} \\{{{{TH}\; 1} = {{TH}\; 1\mspace{14mu} \max \mspace{14mu} \left( {{{when}\mspace{14mu} c} > \beta} \right)}}}\end{matrix} \right\} & (2)\end{matrix}$

With regard to the threshold TH2 according to the present embodiment,the higher the probability, the smaller the threshold TH2. Thereby, inthe case where the current operation mode is the listening mode, thehigher the probability of a topic, the more easily the operation mode isswitched to the specific topic mode even when the reduction inacceptability is small. For example, the threshold TH2 is calculated,for example, by the following equation (3). In equation (3), TH2maxrepresents the maximum value (for example, 0.3) of the threshold TH2,and TH2 min represents the minim value (for example, 0.1) of thethreshold TH2.

TH2=(1−c)×TH2max+c×TH2min  (3)

The threshold TH2 may be calculated, for example, by the followingequation (4). The threshold TH2 calculated by equation (4) is TH2maxwhen c (probability)<α, and is TH2 min when c>β. When α≤c≤β, thethreshold TH2 satisfies TH2min≤TH2≤TH2max, where the larger theprobability c, the smaller the threshold TH2. With regard to theprobability in calculating the thresholds TH1 and TH2, when there are aplurality of topics, the form is illustrated in which, amongprobabilities respectively dealing with the plurality of topics, thelargest probability is used.

$\begin{matrix}\left. \begin{matrix}{{{{TH}\; 2} = {{TH}\; 2\mspace{14mu} \max \mspace{14mu} \left( {{{when}\mspace{14mu} c} < \alpha} \right)}}\mspace{365mu}} \\{{{TH}\; 2} = {{\frac{\beta - c}{\beta - \alpha} \times {TH}\; 2\mspace{14mu} \max} + {\frac{c - \alpha}{\beta - \alpha} \times {TH}\; 2\mspace{14mu} \min \mspace{14mu} \left( {{{when}\mspace{14mu} \alpha} \leq c \leq \beta} \right)}}} \\{{{{TH}\; 2} = {{TH}\; 2\mspace{14mu} \min \mspace{14mu} \left( {{{when}\mspace{14mu} c} > \beta} \right)}}}\end{matrix} \right\} & (2)\end{matrix}$

With reference to FIG. 4, a specific example of a process of selectingan operation mode performed by the selection unit 36 when the currentoperation mode is the listening mode will be described. The solid linein FIG. 4 represents the acceptability, and a dash-dot line representsthe probability of topic A. In FIG. 4, t_(n) represents the current timeat which the probability and the acceptability are estimated by usingthe most recently input utterances, and t_(n−1) represents a time atwhich the probability and the acceptability are estimated by usingutterances input at a time previous to the time t_(n). The case wherethe operation mode selected at the time t_(n−1) by the selection unit36, that is, the current operation mode is the listening mode will nowbe described.

As illustrated in FIG. 4, there is a topic the probability of which isgreater than or equal to the certain value at the time t_(n) (topic A inthe example in FIG. 4). At the time t_(n), the acceptability is greaterthan or equal to the threshold TH1. The reduction R in the acceptabilityat the time t_(n), which is calculated by equation (5) below, is assumedto be greater than or equal to the threshold TH2. Accordingly, theselection unit 36 selects the specific topic mode as the operation modeand selects topic A as a topic for which an interaction proceeds in thespecific topic mode. In equation (5), J_(n−1) represents theacceptability at the time t_(n−1), and J_(n) represents theacceptability at the time t_(n).

R=(J _(n−1) −J _(n))/(t _(n) −t _(n−1))  (5)

The selection unit 36 may set, as the reduction in acceptability, theabsolute value of the slope of a tangent at the time t_(n) of a curve,which is obtained by approximating time-sequential changes in theacceptability by a polynomial or the like, when the slope has a negativevalue.

When the current operation mode is the specific topic mode, when thereis not another topic the probability of which is greater than or equalto the certain value, and when the acceptability is less than thethreshold TH3, the selection unit 36 selects the listening mode as theoperation mode. Accordingly, in this case, the operation mode isswitched from the specific topic mode to the listening mode. Anothertopic as used herein means a topic other than the current topic forwhich an interaction proceeds in the specific topic mode until justbefore the operation mode is switched.

When the current operation mode is the specific topic mode, when thereis not another topic the probability of which is greater than or equalto the certain value, and when the acceptability is greater than orequal to the threshold TH3, the selection unit 36 selects the specifictopic mode as the operation mode. In this case, the selection unit 36selects the current topic as a topic for which the interaction proceedsin the specific topic mode. Accordingly, in this case, the specifictopic mode in which an interaction proceeds for the current topiccontinues.

When the current operation mode is the specific topic mode, when thereis another topic the probability of which is greater than or equal tothe certain value, and when the acceptability is less than the thresholdTH3 or the reduction in acceptability is greater than or equal to thethreshold TH4, the selection unit 36 selects the specific topic mode asthe operation mode. The selection unit 36 selects another topic theprobability of which is greater than or equal to the certain value, as atopic for which an interaction proceeds in the specific topic mode.Accordingly, in this case, while the operation mode remains in thespecific topic mode, the topic is switched. When there are a pluralityof topics the probability of each of which is greater than or equal tothe certain value, the selection unit 36 may select one topic as in thecase where the operation mode is switched from the listening mode to thespecific topic mode as described above. The threshold TH3 is an exampleof the first threshold in the case where the current operation mode inthe disclosed techniques is the second mode, and the threshold TH4 is anexample of the second threshold in the case where the current operationmode in the disclosed techniques is the second mode.

When the current operation mode is the specific topic mode, when thereis another topic the probability of which is greater than or equal tothe certain value, and when the acceptability is greater than or equalto the threshold TH3 and the reduction in acceptability is less than thethreshold TH4, the selection unit 36 selects the specific topic mode asthe operation mode. The selection unit 36 selects the current topic as atopic for which an interaction proceeds in the specific topic mode.Accordingly, in this case, the specific topic mode in which aninteraction proceeds for the current topic continues.

With regard to the threshold TH3 according to the present embodiment,the higher the probability of the current topic, the smaller thethreshold TH3. For example, the threshold TH3 is calculated in the sameway as the threshold TH2. With regard to the threshold TH4 according tothe present embodiment, the higher the probability of the current topic,the larger the threshold TH4. For example, the threshold TH4 iscalculated in the same way as the threshold TH1. Accordingly, when thecurrent operation mode is the specific topic mode, the higher theprobability of the current topic, the more easily the specific topicmode continues, and when there is another topic the probability of whichis greater than or equal to the certain value, the lower the probabilityof the current topic, the more easily the topic is switched to the othertopic.

With reference to FIG. 5 and FIG. 6, specific examples of a process inwhich an operation mode is selected by the selection unit 36 when thecurrent operation mode is the specific topic mode will each bedescribed. In FIG. 5 and FIG. 6, the solid line represents theacceptability and the dash-dot line represents the probability of topicA. The dash-dot-dot line in FIG. 6 represents the probability of topicB. With reference FIG. 5 and FIG. 6, the case where the current topic istopic A will be described.

As illustrated in FIG. 5, there is not a topic the probability of whichis greater than or equal to the certain value at the time t_(n). At thetime t_(n), the acceptability is less than the threshold TH3.Accordingly, the selection unit 36 selects the listening mode as theoperation mode. For example, in this case, the operation mode isswitched from the specific topic mode to the listening mode.

As illustrated in FIG. 6, there is a topic (topic B in the example inFIG. 6) the probability of which is greater than or equal to the certainvalue other than the current topic (topic A in the example in FIG. 6) atthe time t_(n). At the time t_(n), the acceptability is less than thethreshold TH3. Accordingly, the selection unit 36 selects the specifictopic mode as the operation mode and selects topic B the probability ofwhich is greater than or equal to the certain value, as a topic forwhich an interaction proceeds in the specific topic mode. For example,in this case, the specific topic mode continues, and the topic for whichan interaction proceeds in the specific topic mode is switched fromtopic A to topic B.

The generating unit 38 generates text data representing utterancesaccording to the operation mode selected by the selection unit 36.

For example, when the operation mode selected by the selection unit 36is the listening mode, the generating unit 38 generates text datarepresenting utterances that prompt the user to freely make utterancesto collect information of the user. Examples of the utterances generatedby the generating unit 38 in the listening mode include a backchannelresponse and a question about utterances of the user. Examples of theutterances generated by the generating unit 38 in the listening modeinclude utterances such as “Did you go somewhere recently?” and “Didsomething good happen?”.

When the operation mode selected by the selection unit 36 is thespecific topic mode, the generating unit 38 generates text datarepresenting utterances in which the interaction proceeds under theinitiative of the system for a topic selected by the selection unit 36.Examples of utterances generated by the generating unit 38 in thespecific topic mode include utterances according to a scenario built inadvance onto the selected topic and utterances that provide detailedinformation on the selected topic. Examples of the scenario built inadvance include the procedure for cooking food in the case where thetopic is cooking. Examples of the scenario built in advance include theprocedure from determining the destination to booking transportation andaccommodations in the case where the topic is a travel.

The output unit 40 transmits to the interaction device 12 text datarepresenting utterances generated by the generating unit 38, therebycausing the utterances generated by the generating unit 38 to be outputfrom the voice output device 67 of the interaction device 12.

The interaction device 12 may be implemented, for example, by a computer50 illustrated in FIG. 7. The computer 50 includes a central processingunit (CPU) 51, a memory 52 serving as a temporary storage area, and anonvolatile storage unit 53. The computer 50 includes an input andoutput interface (I/F) 54 to which a voice input device 66, such as amicrophone, and a voice output device 67, such as a speaker, arecoupled. The computer 50 includes a read/write (R/W) unit 55 thatcontrols reading and writing of data from and to a storage medium 58 anda network I/F 56 coupled to the network N. The CPU 51, the memory 52,the storage unit 53, the input and output I/F 54, the R/W unit 55, andthe network I/F 56 are coupled via a bus 57.

The storage unit 53 may be implemented by a hard disk drive (HDD), asolid state drive (SSD), a flash memory, or the like. The storage unit53 as a storage medium stores a conversion program 60 that causes thecomputer 50 to function as the interaction device 12. The conversionprogram 60 includes a conversion process 61, a transmitting process 62,and a receiving process 63.

The CPU 51 reads the conversion program 60 from the storage unit 53 andloads the conversion program 60 into the memory 52 to execute theprocesses included in the conversion program 60. The CPU 51 operates asthe conversion unit 20 illustrated in FIG. 2 by executing the conversionprocess 61. The CPU 51 operates as the transmitting unit 22 illustratedin FIG. 2 by executing the transmitting process 62. The CPU 51 operatesas the receiving unit 24 illustrated in FIG. 2 by executing thereceiving process 63. Thus, the computer 50 executing the conversionprogram 60 functions as the interaction device 12. The CPU 51 thatexecutes the processes included in the conversion program 60 ishardware.

The functions achieved by the conversion program 60 may be implementedby, for example, a semiconductor integrated circuit, more specifically,an application-specific integrated circuit (ASIC) or the like.

The interaction control device 14 may be implemented, for example, by acomputer 70 illustrated in FIG. 8. The computer 70 includes a CPU 71,memory 72 as a temporary storage area, and a nonvolatile storage unit73. The computer 70 includes an input and output device 74 that includesa display device, an input device, and the like. The computer 70includes a R/W unit 75 that controls reading and writing of data fromand to a storage medium 78 and a network I/F 76 coupled to the networkN. The CPU 71, the memory 72, the storage unit 73, the input and outputdevice 74, the R/W unit 75, and the network I/F 76 are coupled via a bus77.

The storage unit 73 may be implemented by an HDD, an SSD, a flashmemory, or the like. The storage unit 73 as a storage medium stores aninteraction control program 80 that causes the computer 70 to functionas the interaction control device 14. The interaction control program 80includes an analysis process 81, a probability estimation process 82, anacceptability estimation process 83, a selection process 84, agenerating process 85, and an output process 86.

The CPU 71 reads the interaction control program 80 from the storageunit 73 and loads the interaction control program 80 into the memory 72to execute the processes included in the interaction control program 80.The CPU 71 operates as the analysis unit 30 illustrated in FIG. 3 byexecuting the analysis process 81. The CPU 71 operates as theprobability estimation unit 32 illustrated in FIG. 3 by executing theprobability estimation process 82. The CPU 71 operates as theacceptability estimation unit 34 illustrated in FIG. 3 by executing theacceptability estimation process 83. The CPU 71 operates as theselection unit 36 illustrated in FIG. 3 by executing the selectionprocess 84. The CPU 71 operates as the generating unit 38 illustrated inFIG. 3 by executing the generating process 85. The CPU 71 operates asthe output unit 40 illustrated in FIG. 3 by executing the output process86. Thus, the computer 70 executing the interaction control program 80functions as the interaction control device 14. The CPU 71 that executesthe processes included in the interaction control program 80 ishardware.

The functions achieved by the interaction control program 80 may also beimplemented by, for example, a semiconductor integrated circuit, morespecifically an ASIC or the like.

Operations of the interaction control system 10 according to the presentembodiment will now be described. The interaction device 12 executes theconversion program 60, executing the converting process illustrated inFIG. 9. The converting process illustrated in FIG. 9 is performed, forexample, when the interaction device 12 is powered on or when a startword determined in advance is input to the interaction device 12 via thevoice input device 66.

The interaction control device 14 performs the interaction controlprocess illustrated in FIG. 10 and FIG. 11 by executing the interactioncontrol program 80. The interaction control process illustrated in FIG.10 and FIG. 11 is performed, for example, when the interaction controldevice 14 is powered on or when a start word determined in advance isinput to the interaction device 12 via the voice input device 66 and thestart word is received via a network. In the present embodiment, thecase where the initial operation mode is the listening mode isdescribed.

In step S10 in FIG. 9, the conversion unit 20 waits until receipt ofutterances of the user via the voice input device 66. When theutterances of the user are input via the voice input device 66, thedetermination in step S10 is affirmative and the process proceeds tostep S12. In step S12, the conversion unit 20 converts, to text data,voice data representing the utterances received in step S10.

In step S14, the transmitting unit 22 transmits text data representingutterances of the user obtained by conversion in step S12 to theinteraction control device 14. In step S16, the receiving unit 24 waitsuntil receipt of text data transmitted from the interaction controldevice 14. When the receiving unit 24 receives text data transmitted inresponse to the text data transmitted in step S14 from the interactioncontrol device 14 in step S64 in FIG. 10 described later, thedetermination in step S16 is affirmative. When the determination in stepS16 is affirmative, the process proceeds to step S18.

In step S18, the conversion unit 20 converts the text data received instep S16 to voice data. In step S20, the conversion unit 20 utters aresponse by causing the voice data obtained by conversion in step S18 tobe output from the voice output device 67. Upon completion of step S20,the process returns to step S10.

The converting process illustrated in FIG. 9 terminates, for example,when the interaction device 12 is powered off or when an end worddetermined in advance is input to the interaction device 12 via thevoice input device 66.

In step S30 in FIG. 10, the analysis unit 30 waits until receipt of textdata representing utterances of the user transmitted from theinteraction device 12. When the analysis unit 30 receives text datatransmitted from the interaction device 12 in step S14 in FIG. 9, thedetermination in step S30 is affirmative and the process proceeds tostep S32.

In step S32, the analysis unit 30 performs known natural languageprocessing on the text data received in step S30, thereby performingmorphological analysis, determining the meaning of a sentence, such as aquestion sentence, or a sentence in an affirmative form, a negativeform, or another form, and performing analysis such as estimation ofemotion. In step S34, as described above, the probability estimationunit 32 estimates a topic in which the user is interested, by using thetext data received in step S30, and estimates the probability of theestimated topic in accordance with the determination items (A) to (D)mentioned above.

In step S36, as described above, the acceptability estimation unit 34estimates the acceptability by using the text data received in step S30in accordance with the determination items (E) to (K) mentioned above.The acceptability estimation unit 34 also calculates the reduction inacceptability according to equation (5). In equation (5), t_(n−1)corresponds to a time at which step S36 was performed previously, andt_(n) corresponds to the current time. In equation (5), J_(n−1)corresponds to the acceptability estimated in step S36 performedpreviously, and J_(n) corresponds to the acceptability estimated in stepS38 performed currently.

In step S38, the selection unit 36 determines whether the currentoperation mode is the listening mode. If the determination is negative,that is, the current operation mode is the specific topic mode, theprocess proceeds to step S48; however, if the determination isaffirmative, the process proceeds to step S40.

In step S40, the selection unit 36 determines whether there is a topicthe probability of which is estimated in step S34 to be greater than orequal to the certain value. If the determination is negative, theprocess proceeds to step S46; however, if the determination isaffirmative, the process proceeds to step S42. In step S42, theselection unit 36 determines whether the acceptability estimated in stepS36 is less than the threshold TH1 or whether the reduction inacceptability calculated in step S36 is greater than or equal to thethreshold TH2. If the determination is negative, the process proceeds tostep S46; however, if the determination is affirmative, the processproceeds to step S44. During this determination, the selection unit 36calculates the threshold TH1 by using the probability estimated in stepS34 according to equation (1). During this determination, the selectionunit 36 calculates the threshold TH2 by using the probability estimatedin step S34 according to equation (3).

In step S44, as described above, the selection unit 36 selects thespecific topic mode as the operation mode and selects, as a topic forwhich an interaction proceeds in the specific topic mode, a topic theprobability of which is estimated in step S34 to be greater than orequal to the certain value. Upon completion of step S44, the processproceeds to step S62. In step S46, the selection unit 36 selects thelistening mode as the operation mode. Upon completion of step S46, theprocess proceeds to step S62.

In step S48, as described above, the selection unit 36 determineswhether there is another topic the probability of which is estimated instep S34 to be greater than or equal to the certain value. If thisdetermination is affirmative, the process proceeds to step S50. In stepS50, the selection unit 36 determines whether the acceptabilityestimated in step S36 is less than the threshold TH3 or whether thereduction in acceptability calculated in step S36 is greater than orequal to the threshold TH4. If the determination is negative, theprocess proceeds to step S54; however, if the determination isaffirmative, the process proceeds to step S52. During thisdetermination, as described above, the selection unit 36 calculates thethreshold TH3 in the same way as the selection unit 36 calculates thethreshold TH2 and calculates the threshold TH4 in the same way as theselection unit 36 calculates the threshold TH1.

In step S52, the selection unit 36 selects the specific topic mode asthe operation mode and selects, as a topic for which an interactionproceeds in the specific topic mode, another topic the probability ofwhich is estimated in step S34 to be greater than or equal to thecertain value. Upon completion of step S52, the process proceeds to stepS62.

In step S54, the selection unit 36 selects the specific topic mode asthe operation mode and selects the current topic as a topic for which aninteraction proceeds in the specific topic mode. Upon completion of stepS54, the process proceeds to step S62.

If the determination in step S48 is negative, the process proceeds tostep S56 in FIG. 11. In step S56 in FIG. 11, the selection unit 36determines whether the acceptability estimated in step S36 is less thanthe threshold TH3. If the determination is negative, the processproceeds to step S60; however, if the determination is affirmative, theprocess proceeds to step S58. During this determination, as describedabove, the selection unit 36 calculates the threshold TH3 in the sameway as the selection unit 36 calculates the threshold TH2.

In step S58, the selection unit 36 selects the listening mode as theoperation mode. Upon completion of step S58, the process proceeds tostep S62 in FIG. 10. In step S60, the selection unit 36 selects thespecific topic mode as the operation mode and selects the current topicas a topic for which an interaction proceeds in the specific topic mode.Upon completion of step S60, the process proceeds to step S62 in FIG.10.

In step S62 in FIG. 10, as described above, the generating unit 38generates text data representing utterances according to the operationmode selected through the process described above. For example, whenstep S62 is performed after step S44, step S52, step S54, or step S60,the generating unit 38 generates text data describing that aninteraction proceeds under the initiative of the system for a topicselected in step S44, step S52, step S54, or step S60. In contrast, whenstep S62 is performed after step S46 or step S58, the generating unit 38generates text data of prompting the user to freely make utterances.

In step S64, the output unit 40 transmits the text data generated instep S62 to the interaction device 12, thereby causing the utterancesgenerated by the generating unit 38 to be output from the voice outputdevice 67 of the interaction device 12. Upon completion of step S64, theprocess returns to step S30.

The interaction control process illustrated in FIG. 10 and FIG. 11terminates, for example, when the interaction control device 14 ispowered off or when an end word determined in advance is input to theinteraction device 12 via the voice input device 66.

As described above, according to the present embodiment, in accordancewith the probability that a user is interested in a topic that intereststhe user and the acceptability of an interaction by the user, which ofthe listening mode and the specific topic mode is selected as theoperation mode in which the interaction is performed. Utterancesaccording to the selected operation mode are output from the voiceoutput device 67. Accordingly, it may be suppressed that the user sideor the system side unilaterally utters words to make an interactionmonotonic. As a result, a continuous interaction may be performedwithout boring the user.

According to the present embodiment, the thresholds TH1, TH2, TH3, andTH4 differ in accordance with the probability. Accordingly, a suitableoperation mode in accordance with the probability is selected and, as aresult, the user may further perform a continuous interaction with auser without boring the user.

Second Embodiment

A second embodiment of the disclosed techniques will be described. Theconfiguration of the interaction control system 10, the functionalconfiguration of the interaction device 12, and the configuration of acomputer that functions as the interaction device 12 according to thepresent embodiment are the same as those in the first embodiment, andtherefore description thereof is omitted.

With reference to FIG. 3, the functional configuration of an interactioncontrol device 14A according to the present embodiment will bedescribed. The functional units having the same functions as thefunctional units of the interaction control device 14 according to thefirst embodiment are denoted by the same reference numerals anddescription thereof is omitted. As illustrated in FIG. 3, theinteraction control device 14A includes the analysis unit 30, theprobability estimation unit 32, the acceptability estimation unit 34,the selection unit 36, a generating unit 38A, and the output unit 40.

The generating unit 38A has, in addition to the functions of thegenerating unit 38 according to the first embodiment, the followingfunctions. When the current operation mode differs from the operationmode selected by the selection unit 36, the generating unit 38Agenerates text data representing utterances including notifying the userof switching of the operation mode. For example, when the operation modeis switched from the listening mode to the specific topic mode, thegenerating unit 38A generates text data that represents utterancesincluding notifying the user that the system itself takes initiative inthe interaction. Examples of the utterances including notifying the userthat the system itself takes initiative in the interaction include“Please listen to me.” and “Apart from that, I want to talk about A.” Inthis example, “A” represents a topic for which an interaction proceedsin the specific topic mode selected by the selection unit 36.

When the operation mode is switched from the specific topic mode to thelistening mode, the generating unit 38A generates text data thatrepresents utterances including notifying the user of transfer of theinteraction initiative to the user. Examples of the utterances includingnotifying the user of transfer of the interaction initiative to the userinclude “What do you think?”, “Speaking of A, is there anything else?”,and “Do you have anything that you want to talk about?” In this example,“A” represents a topic for which an interaction has proceeded in thespecific topic mode.

When the specific topic mode continues as the operation mode and thetopic is switched, the generating unit 38A generates text data thatrepresents utterances including notifying the user that the topic forwhich the interaction proceeds will be changed to a new topic. Examplesof the utterances including notifying the user that the topic for whichthe interaction proceeds will be changed to a new topic include “By theway, I want to talk about A” and “By the way, do you know anything aboutA?”. In this example, “A” represents a topic for which an interactionproceeds in the specific topic mode.

The interaction control device 14A may be implemented, for example, bythe computer 70 illustrated in FIG. 8. The same or similar elements asthose in the first embodiment illustrated in FIG. 8 are denoted by thesame or similar reference numerals, and repetitive descriptions areomitted. The storage unit 73 of the computer 70 stores an interactioncontrol program 80A that causes the computer 70 to function as theinteraction control device 14A. The interaction control program 80Aincludes the analysis process 81, the probability estimation process 82,the acceptability estimation process 83, the selection process 84, agenerating process 85A, and the output process 86.

The CPU 71 reads the interaction control program 80A from the storageunit 73 and loads the interaction control program 80A into the memory 72to execute the processes included in the interaction control program80A. The CPU 71 operates as the analysis unit 30 illustrated in FIG. 3by executing the analysis process 81. The CPU 71 operates as theprobability estimation unit 32 illustrated in FIG. 3 by executing theprobability estimation process 82. The CPU 71 operates as theacceptability estimation unit 34 illustrated in FIG. 3 by executing theacceptability estimation process 83. The CPU 71 operates as theselection unit 36 illustrated in FIG. 3 by executing the selectionprocess 84. The CPU 71 operates as the generating unit 38A illustratedin FIG. 3 by executing the generating process 85A. The CPU 71 operatesas the output unit 40 illustrated in FIG. 3 by executing the outputprocess 86. Thus, the computer 70 executing the interaction controlprogram 80A functions as the interaction control device 14A. The CPU 71that executes the processes included in the interaction control program80A is hardware.

The functions achieved by the interaction control program 80A may alsobe implemented by, for example, a semiconductor integrated circuit, morespecifically an ASIC or the like.

Operations of the interaction control system 10 according to the presentembodiment will now be described. The converting process performed bythe interaction device 12 according to the present embodiment is thesame as in the first embodiment, and therefore description thereof isomitted.

The interaction control device 14A performs the interaction controlprocess illustrated in FIG. 12 and FIG. 11 by executing the interactioncontrol program 80A. Of the interaction control process performed by theinteraction control device 14A according to the present embodiment, thepart illustrated in FIG. 11 is the same as in the first embodiment, andtherefore description thereof is omitted. The steps in FIG. 12 that arethe same as illustrated in FIG. 10 are denoted by the same referencenumerals, and description thereof is omitted. The interaction controlprocess illustrated in FIG. 11 and FIG. 12 is performed, for example,when the interaction control device 14A is powered on or when a startword determined in advance is input to the interaction device 12 via thevoice input device 66. In the present embodiment, the case where theinitial operation mode is the listening mode is described.

Upon completion of step S44, step S46, step S52, or step S54 in FIG. 12,or step S58 or step S60 in FIG. 11, the process proceeds to step S70 inFIG. 12.

In step S70, the generating unit 38A determines whether the operationmode may be switched from the listening mode to the specific topic mode.If the determination is negative, the process proceeds to step S74;however, if the determination is affirmative, the process proceeds tostep S72. When step S70 is performed after step S44, the determinationin step S70 is affirmative. When step S70 is performed after step S46,step S52, step S54, step S58 or step S60, the determination in step S70is negative.

In step S72, as described above, the generating unit 38A generates textdata that represents utterances including notifying the user that thesystem itself takes initiative in the interaction. Upon completion ofstep S72, the process proceeds to step S64A.

In step S74, the generating unit 38A determines whether the operationmode may be switched from the specific topic mode to the listening mode.If the determination is negative, the process proceeds to step S78;however, if the determination is affirmative, the process proceeds tostep S76. When step S74 is performed after step S58, the determinationin step S74 is affirmative, and when step S74 is performed after stepS46, step S52, step S54, or step S60, the determination in step S74 isnegative.

In step S76, the generating unit 38A generates text data that representsutterances including notifying the user of transfer of the interactioninitiative to the user. Upon completion of step S76, the processproceeds to step S64A.

In step S78, the generating unit 38A determines whether the specifictopic mode continues as the operation mode and the topic may beswitched. If the determination is negative, the process proceeds to stepS62; however, if the determination is affirmative, the process proceedsto step S80. When step S78 is performed after step S52, thedetermination in step S78 is affirmative, and when step S78 is performedafter step S46, step S54, or step S60, the determination in step S78 isnegative.

In step S80, the generating unit 38A generates text data that representsutterances including notifying the user that the topic for which theinteraction proceeds will be changed to a new topic. Upon completion ofstep S80, the process proceeds to step S64A. Upon completion of stepS62, the process proceeds to step S64A.

In step S64A, the output unit 40 transmits to the interaction device 12the text data that represents utterances generated in step S62, stepS72, step S76, or step S80. Thus, the output unit 40 causes theutterances generated by the generating unit 38A to be output from thevoice output device 67 of the interaction device 12. Upon completion ofstep S64A, the process returns to step S30.

The interaction control process illustrated in FIG. 11 and FIG. 12terminates, for example, when the interaction control device 14A ispowered off or when an end word determined in advance is input to theinteraction device 12 via the voice input device 66.

In the second embodiment, when the operation mode is switched form thelistening mode to the specific topic mode, the generating unit 38A maygenerate text data that represents utterances including notifying theuser that the topic for which the interaction proceeds will be changedto a new topic.

In the second embodiment, when the operation mode is switched from thelistening mode to the specific topic mode even though the acceptabilityis greater than or equal to a threshold TH5, the generating unit 38Agenerates utterances including notifying the user that the system itselftakes initiative in the interaction. In this case, when theacceptability is less than or equal to the threshold TH5 and theoperation mode is switched form the listening mode to the specific topicmode, the generating unit 38A generates text data that representsutterances including notifying the user that the topic for which theinteraction proceeds will be changed to a new topic. The form isillustrated in which, as the threshold TH5 in this case, for example, avalue determined in advance is applied as the lower limit value (forexample, 0.7) of a value indicating that the user is satisfied with aninteraction with the interaction control system 10.

As described above, according to the present embodiment, effects similarto those in the first embodiment may be obtained. According to thepresent embodiment, when the current operation mode differs from theselected operation mode, utterances including notifying the user ofswitching of the operation mode are generated. Accordingly, the usereasily keeps track of which of the user and the system seizes initiativein an interaction. This may result in a smooth interaction with theuser.

In the aforementioned embodiments, the examples in which the disclosedtechniques are applied to an interaction control system that makes avoice interaction with the user have been described. However, thedisclosed techniques are not limited to this. For example, the form inwhich the disclosed techniques are applied to an interaction controlsystem that makes an interaction with the user by using text, such as atext chat, may be employed. In this case, text input by the usercorresponds to input from the user in the disclosed techniques, and textoutput to a display device or the like of the interaction device 12corresponds to an interaction output in the disclosed techniques. Thecombination of an input from the user and an interaction output may beany of a combination of voice and voice, a combination of voice andtext, a combination of text and voice, and a combination of text andtext.

In the aforementioned embodiments, the examples in which the interactioncontrol system 10 is implemented by the interaction device 12 and theinteraction control device 14 or 14A have been described. However, theinteraction control system 10 is not limited to this. The form in whichthe interaction control system 10 is implemented by the interactiondevice 12 may be employed. In this case, the form in which theinteraction device 12 includes the functions included in the interactioncontrol device 14 or 14A is illustrated.

In the aforementioned embodiments, when the current operation mode isthe listening mode, the operation mode may be selected by using theacceptability or the reduction in acceptability instead of theprobability. In this case, the process in step S40 in FIG. 10 isunnecessary.

In the aforementioned embodiments, the cases where the thresholds TH1,TH2, TH3, and TH4 differ in accordance with the probability have beendescribed. However, these thresholds are not limited to this. At leastone of the thresholds TH1, TH2, TH3, and TH4 may be a fixed valuedetermined in advance.

In the aforementioned present embodiments, the case where the initialoperation mode is the listening mode has been described. However, theinitial operation mode is not limited to this. The initial operationmode may be the specific topic mode. In this case, the form isillustrated in which a general topic such as weather, a popular topic, atopic covered in the news, or the like is applied as the initial topic.

In the aforementioned embodiments, the acceptability may have a valuesuch that the higher the degree to which the user accepts an interactionwith the interaction control system 10, the smaller the value. In thiscase, the form is illustrated in which the magnitude relationship amongvalues related to the acceptability is opposite to that in theaforementioned embodiments. In the aforementioned embodiments, thehigher the likelihood that the user is interested in a topic, thesmaller the probability may be. In this case, the form is illustrated inwhich the magnitude relationship among values related to the probabilityis opposite to that in the aforementioned embodiments.

In the aforementioned embodiments, the manner in which the conversionprogram 60 is stored (installed) in advance in the storage unit 53 hasbeen described. However, the conversion program 60 is not limited tothis. The conversion program 60 may be provided in a form of a storagemedium, such as a compact disc read-only memory (CD-ROM), a digitalversatile disc (DVD)-ROM, a Universal Serial Bus (USB) memory, or amemory card, in which the conversion program 60 is stored.

In the aforementioned embodiments, the manner in which the interactioncontrol program 80 or 80A is stored (installed) in advance in thestorage unit 73 has been described. However, the manner of storage ofthe interaction control program 80 or 80A is not limited to this. Theinteraction control program 80 or 80A may be provided in a form of astorage medium, such as a CD-ROM, a DVD-ROM, a USB memory, or a memorycard, in which the interaction control program 80 or 80A is stored.

All examples and conditional language provided herein are intended forthe pedagogical purposes of aiding the reader in understanding theinvention and the concepts contributed by the inventor to further theart, and are not to be construed as limitations to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of the superiority andinferiority of the invention. Although one or more embodiments of thepresent invention have been described in detail, it should be understoodthat the various changes, substitutions, and alterations could be madehereto without departing from the spirit and scope of the invention.

What is claimed is:
 1. A non-transitory, computer-readable recordingmedium having stored therein a program for causing a computer to executea process comprising: estimating, based on an input from a user to aninteraction performed during a conversation between the user and thecomputer, an interest degree indicating a degree of interest of the userin a first topic included in the interaction; estimating, based on theinput from the user to the interaction, acceptability of the interactionby the user; selecting, in accordance with the interest degree and theacceptability, as an operation mode for performing the interaction, oneof a first mode of leaving an interaction initiative to the user and asecond mode in which the interaction proceeds under an initiative of asystem for a specific topic; generating interaction data according tothe selected operation mode; and causing an output device to output thegenerated interaction data.
 2. The non-transitory, computer-readablerecording medium of claim 1, wherein: the acceptability takes a valuethat becomes greater as a degree to which the user accepts theinteraction becomes higher; the interest degree takes a value thatbecomes greater as a likelihood that the user is interested in the firsttopic becomes higher; and the selecting includes selecting the secondmode as the operation mode when the operation mode at present is thefirst mode, and when the acceptability is less than a first thresholdwhose value becomes greater as the interest degree becomes higher, or areduction in the acceptability is greater than a second threshold whosevalue becomes smaller as the interest degree becomes higher.
 3. Thenon-transitory, computer-readable recording medium of claim 2, whereinthe selecting includes selecting the second mode as the operation modewhen there is a second topic for which the interest degree is higherthan or equal to a certain value.
 4. The non-transitory,computer-readable recording medium of claim 1, wherein: theacceptability takes a value that becomes greater as a degree to whichthe user accepts the interaction becomes higher; and the selectingincludes selecting the first mode as the operation mode when theoperation mode at present is the second mode, and when the acceptabilityis less than a second threshold whose value becomes smaller as theinterest degree becomes higher.
 5. The non-transitory, computer-readablerecording medium of claim 1, wherein: the acceptability takes a valuethat becomes greater as a degree to which the user accepts theinteraction becomes higher; the interest degree takes a value thatbecomes greater as a likelihood that the user is interested in the firsttopic becomes higher; and the process comprises, when the operation modeat present is the second mode, when the acceptability is less than afirst threshold whose value becomes greater as the interest degreebecomes higher, or a reduction in the acceptability is greater than orequal to a second threshold whose value becomes smaller as the interestdegree becomes higher, and when there is a second topic for which theinterest degree is greater than or equal to a certain value, continuinga current mode of the operation mode and generating the interaction dataregarding the second topic.
 6. The non-transitory, computer-readablerecording medium of claim 5, wherein: the first threshold is a valuethat becomes smaller as the interest degree for a current topic becomeshigher; and the second threshold is a value that becomes larger as theinterest degree for the current topic becomes higher.
 7. Thenon-transitory, computer-readable recording medium of claim 1, whereinthe interest degree decreases with lapse of time.
 8. The non-transitory,computer-readable recording medium of claim 1, the process comprisingwhen the operation mode at present differs from the selected operationmode, generating an interaction output including notifying the user ofswitching of the operation mode.
 9. The non-transitory,computer-readable recording medium of claim 8, wherein: theacceptability is a value that becomes greater as the first degree ofinterest becomes higher; and the process comprises generating aninteraction output including notifying the user that a system side takesinitiative in an interaction when the operation mode at present is thefirst mode, and when the selected operation mode is the second mode. 10.An apparatus comprising: a memory; and a processor coupled to the memoryand configured to: estimate, based on an input from a user to aninteraction performed during a conversation between the user and thecomputer, an interest degree indicating a degree of interest of the userin a first topic included in the interaction; estimate, based on theinput from the user to the interaction, acceptability of the interactionby the user; select, in accordance with the interest degree and theacceptability, as an operation mode for performing the interaction, oneof a first mode of leaving an interaction initiative to the user and asecond mode in which the interaction proceeds under an initiative of asystem for a specific topic; generate interaction data according to theselected operation mode; and cause an output device to output thegenerated interaction data.
 11. The apparatus of claim 10, wherein: theacceptability takes a value that becomes greater as a degree to whichthe user accepts the interaction becomes higher; the interest degreetakes a value that becomes greater as a likelihood that the user isinterested in the first topic becomes higher; and the processor isconfigured to select the second mode as the operation mode when theoperation mode at present is the first mode, and when the acceptabilityis less than a first threshold whose value becomes greater as theinterest degree becomes higher, or a reduction in the acceptability isgreater than a second threshold whose value becomes smaller as theinterest degree becomes higher.
 12. The apparatus of claim 11, whereinthe processor is configured to select the second mode as the operationmode when there is a second topic for which the interest degree ishigher than or equal to a certain value.
 13. The apparatus of claim 10,wherein: the acceptability takes a value that becomes greater as adegree to which the user accepts the interaction becomes higher; and theprocessor is configured to select the first mode as the operation modewhen the operation mode at present is the second mode, and when theacceptability is less than a second threshold whose value becomessmaller as the interest degree becomes higher.
 14. The apparatus ofclaim 10, wherein: the acceptability takes a value that becomes greateras a degree to which the user accepts the interaction becomes higher;the interest degree takes a value that becomes greater as a likelihoodthat the user is interested in the first topic becomes higher; and theprocessor is configured to, when the operation mode at present is thesecond mode, when the acceptability is less than a first threshold whosevalue becomes greater as the interest degree becomes higher, or areduction in the acceptability is greater than or equal to a secondthreshold whose value becomes smaller as the interest degree becomeshigher, and when there is a second topic for which the interest degreeis greater than or equal to a certain value, continue a current mode ofthe operation mode and generate the interaction data regarding thesecond topic.
 15. The apparatus of claim 14, wherein: the firstthreshold is a value that becomes smaller as the interest degree for acurrent topic becomes higher; and the second threshold is a value thatbecomes larger as the interest degree for the current topic becomeshigher.
 16. The apparatus of claim 10, wherein the interest degreedecreases with lapse of time.
 17. A method performed by a computer, themethod comprising: estimating, based on an input from a user to aninteraction performed during a conversation between the user and thecomputer, an interest degree indicating a degree of interest of the userin a first topic included in the interaction; estimating, based on theinput from the user to the interaction, acceptability of the interactionby the user; selecting, in accordance with the interest degree and theacceptability, as an operation mode for performing the interaction, oneof a first mode of leaving an interaction initiative to the user and asecond mode in which the interaction proceeds under an initiative of asystem for a specific topic; generating interaction data according tothe selected operation mode; and causing an output device to output thegenerated interaction data.